1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and a method for manufacturing the same.
2. Discussion of the Related Art
Among various flat displays, liquid crystal display (LCD) devices, plasma display panel (PDP) devices, field emission display (FED) devices, vacuum fluorescent display (VFD) devices, etc. are actively being studied and researched. Among these, LCD devices have attracted especially great attention because of their high picture quality, easy operation, mass production capability, etc.
An LCD device displays information on a screen using the refractivity and anisotropy of a liquid crystal material. The LCD device includes lower and upper substrates with a liquid crystal layer formed between the lower and upper substrates. Here, the liquid crystal layer functions as a switch for controlling the transmittance of light. In addition, spacers are provided between the lower and upper substrates to maintain a predetermined gap between the lower and upper substrates.
In a related art LCD panel, a column spacer is formed on one of two substrates facing each other, and the two substrates are sealed by a sealant. The column spacer is not bonded to the other facing substrate. Accordingly, in a large-sized display screen, the gap between the substrates is changed due to an external pressure on the screen, for example, by the touch of the user's finger. Thus, an electrode interval is also changed with the change of gap, and defects are generated on the display screen.
To solve this problem, the column spacer is cured by pressure and heat treatments so that the column spacer is bonded to the other facing substrate (for example, Japanese Patent Publication No. 2003-330029). However, if applying the pressure and heat, the column spacer is deformed due to the pressure when the two substrates are joined. Thus, precise gap control cannot be achieved.
To overcome this problem, an adhesive layer is formed on the upper surface of the column spacer by printing. That is, the column spacer is bonded to the other facing substrate by the adhesive layer (for example, Japanese Patent Publication No. 2004-12772).
If the adhesive layer is formed by printing, additional steps in manufacturing the device are necessary, thereby increasing the manufacturing cost and decreasing the yield. Also, the sealant for sealing the gap of the two substrates is formed of a thermocuring resin which has the adhesive property by itself. The sealant is formed on any one of the two substrates, and is bonded to the other facing substrate by pressure and heat. If using the adhesive layer, various problems (for example, incomplete curing or foreign material to the liquid crystal) may occur.